The present invention relates to the intravascular ultrasound analysis arts. It finds particular application to a method and system for quantitative component identification within a vascular object including characterization of plaque. It will be appreciated that the present invention will also find application to other types objects which can be scanned with an ultrasonic device.
Ultrasonic imaging of portions of a patient's body provides a useful tool in various areas of medical practice for determining the best type and course of treatment. Imaging of the coronary vessels of a patient by ultrasonic techniques can provide physicians with valuable information. For example, the image data may show the extent of a stenosis in a patient, reveal progression of disease, help determine whether procedures such as angioplasty or atherectomy are indicated or whether more invasive procedures may be warranted.
In a typical ultrasound imaging system, an ultrasonic transducer is attached to the end of a catheter that is carefully maneuvered through a patient's body to a point of interest such as within a blood vessel. The transducer is a single-element crystal or probe which is mechanically scanned or rotated back and forth to cover a sector over a selected angular range. Acoustic signals are transmitted during the scanning and echoes from these acoustic signals are received to provide data representative of the density of tissue over the sector. As the probe is swept through the sector, many acoustic lines are processed building up a sector-shaped image of the patient. After the data is collected, images of the blood vessel are reconstructed using well-known techniques and the images are visually analyzed by a cardiologist to assess the vessel components and plaque content.
Typically, the ultrasonic image data is transferred to a VHS videotape, digitized and then analyzed. This process, however, loses image resolution since the videotape has a lower resolution than the originally collected ultrasound data. Losing image resolution may result in an inaccurate evaluation of a vessel and its plaque content. Furthermore, certain image characteristics like brightness and contrast will be different for different patients or could vary for the same patient if the cardiologist varies the settings on the IVUS console. The images that are recorded on the videotapes are the same images viewed on the IVUS console screen and, thus, subject to the settings on the console. Since plaque is identified by its appearance on the screen, errors may occur in the analysis if the screen settings have been modified.
The present invention provides a new and unique intravascular ultrasonic analysis method and system with cures the above problems and others.